+
+function drawPreview() {
+ let canvas = document.getElementById("mbrotPreview");
+ let context = canvas.getContext("2d");
+
+ let Cr_min = parseFloat(document.getElementById("Cr_min").value);
+ let Cr_max = parseFloat(document.getElementById("Cr_max").value);
+ if ((Cr_min < -2) || (Cr_min > 2) ||
+ (Cr_max < -2) || (Cr_max > 2) || (Cr_min >= Cr_max)) {
+ Cr_min = -2.0; Cr_max = 1.0;
+ }
+
+ let Ci_min = parseFloat(document.getElementById("Ci_min").value);
+ let Ci_max = parseFloat(document.getElementById("Ci_max").value);
+ if ((Ci_min < -2) || (Ci_min > 2) ||
+ (Ci_max < -2) || (Ci_max > 2) || (Ci_min >= Ci_max)) {
+ Ci_min = -2.0; Ci_max = 1.0;
+ }
+
+ let iterMax = gPref.getIntPref("mandelbrot.iteration_max");
+ let algorithm = gPref.getCharPref("mandelbrot.use_algorithm");
+
+ context.fillStyle = "rgba(255, 255, 255, 127)";
+ context.fillRect(0, 0, canvas.width, canvas.height);
+
+ try {
+ var currentPalette = gPref.getCharPref("mandelbrot.color_palette");
+ }
+ catch(e) {
+ var currentPalette = '';
+ }
+ if (!currentPalette.length) {
+ currentPalette = 'kairo';
+ }
+ gColorPalette = getColorPalette(currentPalette);
+
+ drawLine(0, [Cr_min, Cr_max, Ci_min, Ci_max],
+ canvas, context, iterMax, algorithm);
+}